1. Field of the Invention
The present invention relates to a throttle control apparatus mounted on a motorcycle handlebar, for allowing a user of the motorcycle to remotely control a throttle valve of an engine while operating the motorcycle.
2. Background Art
In a motorcycle, a throttle grip is mounted on a handlebar. When a rider rotates the throttle grip in the circumferential direction, a throttle valve mounted in an intake passage of an internal combustion engine performs an open/close operation.
It is necessary to control the open/close operation of the throttle valve in such a manner that an open/close amount of the throttle valve corresponds to a rotational amount of the throttle grip. Accordingly, a throttle control apparatus is mounted on a handlebar, and a pivotal movement of the throttle grip is detected by the throttle control apparatus.
This type of throttle control apparatus includes a rotor, which is rotated in an interlocking manner with the manipulation of the throttle grip, and a housing which houses the rotor. As shown in FIG. 4 of patent document 1, a return spring is engaged with the rotor and the housing, for returning the rotated rotor to an original position. One end of the return spring is engaged with the rotor, and the other end of the return spring is engaged with the housing.
When a rider rotates the throttle grip along the circumferential direction, the rotor is correspondingly rotated, and the return spring extends. Conversely, when the rider returns the throttle grip to its original position by turning it in the opposite direction, the extended return spring returns by an elastic action to its original shape and configuration and, as a result, the rotor also returns to the original position (angle) thereof.
[Patent Document 1] JP-A-2009-287411
The throttle control apparatus according to the prior art having the above-mentioned constitution is assembled in accordance with steps where an assembly including the rotor and a position senor which detects a rotational angle of the rotor is inserted on to a handlebar and, thereafter, a housing is mounted so as to cover the assembly. Although one end of the return spring is already engaged with the rotor, it is not easy to engage the other end of the return spring to the housing. That is, the so-called assembling property is not favorable.
Further, in this known arrangement, one end of the return spring and an engaging hole formed in the housing are aligned with each other and, further, the position of the housing is adjusted after such alignment and hence, a tension acts on the return spring. When the tension is excessively large, there may be a case where an undesired stress is applied to the return spring. Assuming a case where such a state occurs, there is a possibility that quality (particularly durability) of the return spring will differ between a return spring to which a large amount of tension is applied and a return spring to which a small amount of tension is applied.